503 Errors / LSAPI Packet Header is Invalid

I'm getting intermittent 503 errors on the checkout page of my shopping cart. This appears to occur after the payment has been passed to the processor, because the payment is successful, but then it returns the error. Upon reviewing the error log, I see the following:

That's because lsphp and lshttpd communicated with each other using File handle 1 (STDOUT).

We just released LiteSpeed PHP SAPI 4.9 to address this issue.
If you use cPanel, just Build matching PHP binary again, you probably need to switch back to Apache, and remove /usr/local/lsws/fcgi-bin/lsphp-5.2.x in order to rebuild PHP binary.
If you build PHP binary manually, just download the latest php-litespeed package.